The pressurized water reactor uses pressurized light water as a coolant and moderator, and the water does not boil in the reactor. Nuclear fuel is low enriched uranium. It is recognized by the world as a nuclear reactor with mature large-scale technology and safe operation and economy. The AP1000 can be used as a representative product of the third generation of pressurized water reactor nuclear power plants.
The main parameters of the AP1000 third-generation nuclear power plant steam generator (Steam Generator):
Heat exchange area11500m2Primary side designed pressure172bar · aSecondary side designed pressure82.5bar · aHeat exchange power1707.5MWExport steam pressure57.5bar · aSteam flow rate943.7kg/sFeed water temperature226.7°C.Primary side inlet temperature321.1°C.Primary side outlet temperature280.7°C.Outlet steam temperature272.8°C.Secondary side designed temperature315.6°C.
The main parameters of the AP1000 third-generation nuclear power plant steam turbine generator:
Turbine typesingle shaft, four cylinder six exhauststeamLast-stage blade length1371.6 mm (a longer last-stage bladeis used after introduction in China)Rotational speed1800 rpm (modified to 1500 rpm afterintroduction in China)Back pressure8.48 kPaOutput power1,199,500 kW (thermal balancevalue)Turbine heat rate10405.7 kJ/kWh (excluding electricpump power)Thermal efficiency34.6% (excluding electric pumppower)Generator cooling methodwater hydrogen hydrogenHydrogen pressure0.517 MPaRated output apparent power1375 MVAPower factor0.9
The saturated steam generated by the two steam generators is sent to the steam turbine high-pressure cylinder by the second circuit main steam system, and after the expansion work of the steam turbine high-pressure cylinder, the steam is discharged into two external steam-water separation reheaters; under the rated load, the external steam-water separation reheater reduces the humidity of 10%-13% contained in the steam exhaust of the steam turbine to about 0.17% or less. The external steam-water separation reheater has a two-stage reheater, and the first stage uses steam admission of the high-pressure cylinder as a heat source, and the second stage uses the main steam as a heat source, to heat the steam entering the reheater to a superheated state. The steam is heated and then enters three dual-flow turbine low-pressure cylinders through six pipes; part of the steam from the high-pressure cylinder and the low-pressure cylinder is extracted out to heat the feed water and condensate. The main condenser deoxidizes the condensate and transfers the waste heat to the circulating water system; the feed water is injected into the steam generator by the second circuit main feed pump; the steam turbine provides the steam extraction for the six-stage feed water and condensate heating; the extraction point of the high-pressure cylinder provides steam extraction for the number one high-pressure heater, and the high-pressure cylinder steam exhaust provides steam extraction to the deaerator. The third, fourth, fifth, and sixth-stage extraction points of the low-pressure cylinder supply steam extraction for the number three, number four, number five and number sixth low-pressure heaters, respectively, and the number five low-pressure heater and the number six low-pressure heater are usually arranged in the throat of the condenser.
Nuclear power plants that have been put into commercial operation in China (including Taiwan) are almost all pressurized water reactors; from the perspectives of technology, safety, economy, environmental protection and industrial characteristics, pressurized water reactor nuclear power units should not participate in power grid peaking, especially in frequent and drastic load adjustment.
According to the working temperature and the power of the unit, the heavy-duty gas turbines for power stations are divided into eight classes: A-B-C-D-E-F-G-H. The higher the intake temperature of the gas turbine, the higher the unit power, the higher the class, the higher the thermal efficiency, and the higher the steam exhaust temperature of the gas turbine.
The prior art gas turbine generally forms a gas-steam combined circulation system with a waste heat boiler and a steam turbine of the prior art; the steam turbine is or not reheated, has no steam extraction port, and has a medium and low-pressure supplemental steam inlet; the steam turbine is equipped with necessary auxiliary machines, such as condensate pump, circulating water pump, condenser, vacuum pump, cooling tower, lubricating oil system, control oil system, bypass system, etc.; the waste heat boiler is usually designed to operate under double pressures or triple pressures, respectively providing superheated steam of different pressures, each pressure having its own economizer, evaporator, steam drum and superheater; usually power generation of the gas turbine-driven generators accounts for ⅔ or more of the gas-steam combined cycle unit; power generation of the steam turbine-driven generators accounts for about ⅓ or less of the gas-steam combined cycle unit.